COOPERSTOWN, N.Y. -- Seventy-five years ago, the men who made up baseball's elite climbed off a locomotive-drawn train near this little hamlet and set off for the ceremony that would commemorate the alleged 100th anniversary of the game's birth.

The day marked the opening of the National Baseball Hall of Fame and Museum and was heralded by the induction of 26 players, executives, managers and pioneers on the steps of the new red-bricked edifice, the classes of 1936-39. Lou Gehrig couldn't be there because of his fatal illness.

To honor the Hall's 75th birthday on Thursday, Hall of Famers Cal Ripken Jr. and Phil Niekro will be featured guests at the museum, which Commissioner Kenesaw Mountain Landis dedicated in 1939 not only to those who were honored there on that day, "but to all Americans."

"To lovers of sportsmanship and clean minds because those are the principles of baseball," the sport's first Commissioner said.

Thursday's event, which was to be held outside the museum, will instead take place inside due to a forecast of rain. The first 2,000 fans through the doors of the museum will receive a 75th anniversary commemorative keychain. The museum will open at 9 a.m. ET, with admission to the ceremony in the gallery available on a first-come, first-served, standing-room only basis.

Niekro was a last-minute replacement at the ceremony for Joe Morgan, who is undergoing knee replacement surgery and couldn't attend.

Hall officials will unveil a new gallery in honor of Babe Ruth, bringing out numerous artifacts from the archives in honor of the 100th anniversary of the Babe breaking into the game.

Ruth was there that day 75 years ago, along with a treasure trove that included Walter Johnson, Cy Young, Honus Wagner, Tris Speaker, Eddie Collins, Napoleon Lajoie, George Sisler, Grover Cleveland Alexander and Connie Mack. All of them took that famous train trip. Ty Cobb arrived late because he and his son had booked their own train into nearby Albany and rented a car for the drive. Cobb made his grand appearance well after Hall founder Stephen C. Clark began the ceremony.

There were about 15,000 people packing Main Street outside the new museum, far fewer than the 50,000 expected this coming July 27, when pitchers Greg Maddux and Tom Glavine, slugger Frank Thomas, and managers Tony La Russa, Joe Torre and Bobby Cox will be inducted behind the nearby Clark Sports Center. Newsreels from that long ago day show the proceedings in grainy black and white.

"It was pretty special," said Jeff Idelson, the Hall's current president. "The main entrance to the museum is just a short underhand toss from the original steps where we opened."

That baseball's most hallowed institution found its way to this town on the banks of picturesque Lake Otsego is just a quirk of history because of the way a commission perceived it.

At first, baseball was considered to be an offshoot of the British sport rounders, a form of cricket. Baseball was the great American game, said A.G. Spalding, who didn't believe it. During the early 20th century, the former player and sporting goods magnate established the Mills Commission to determine the origin of baseball.

The commission sought memories of citizens from around the country, and Abner Graves, a former Cooperstown resident living in Colorado, wrote to say he was in Cooperstown in 1839 when Abner Doubleday invented baseball. Doubleday would go on to become a decorated general for the Union Army in the Civil War.

"Of course, Spalding loved the story," recalled Bill Francis, a historian for the museum. "How could he not like the story of a future Civil War hero inventing baseball? The commission, and especially Spalding, really embraced the story that baseball was invented in Cooperstown."

To substantiate the story, a misshapen ball allegedly belonging to Doubleday was discovered in a trunk left at a house once owned by Graves in Fly Creek, about three miles from Cooperstown. What is now known as the "Doubleday baseball" was considered to be the first known ball used in the first game, and Clark paid five dollars for it.

Clark, whose granddaughter, Jane Forbes Clark, is the current board chair of the Hall of Fame, used the ball to open a small baseball museum on Main Street, located across from the current Museum. At the time, a high school gymnasium sat on a portion of the property where the new museum would be constructed. The town fathers jumped on the project as a way to draw tourists to upstate New York.

Because of Clark's persistence, Ford Frick, then the National League president and a future Commissioner, prevailed on Landis to endorse the concept. By 1935, he did and that got the ball rolling.

While Hall officials established rules to vote in the first inductees, Clark, a landowner and businessman, used some of his vast fortune to construct the museum at the cost of $100,000, aiming at an opening in 1939 -- the 100th anniversary of Doubleday supposedly inventing baseball in Cooperstown. Frank Whiting, a local architect, designed the original building.

There was one big problem, though. The Doubleday story wasn't true. He was a cadet at West Point in 1839 and was nowhere near Cooperstown when he supposedly founded the game. By the time the museum opened, the Doubleday story had been debunked.

Even so, "They had bought into the Doubleday story. There was no reason for the Hall to even be there if you didn't buy into that story," said John Thorn, MLB's official historian.

The family of Alexander Cartwright, who founded the Knickerbocker Base Ball Club of New York City, contested the Doubleday tale, saying Cartwright had in fact invented the game and was "The Father of Baseball." As a compromise, Cartwright was elected to the Hall by the Veterans Committee in 1938 and inducted with the others in 1939.

"The concession was made that Doubleday would get his building and Cartwright would get his plaque," Thorn said. "And I leave it to you to judge who got the better of the deal. In fact, later research revealed that neither should have been regarded as 'The Father of Baseball.'"

That didn't stop locals from also erecting Doubleday Field, which still stands down the street from the museum and remains named for the general. After the inaugural induction, the first Hall of Fame Game was played there and each of the 16 Major League teams sent two players to play.

Wagner and Collins chose sides, and the Wagners won, 4-2. Ruth, who retired in 1935, pinch-hit and popped out foul.